WO1999041594A1

WO1999041594A1 - Determining surface plasmon resonance using spatially or time-modified layers

Info

Publication number: WO1999041594A1
Application number: PCT/EP1999/000895
Authority: WO
Inventors: Gunnar Brink; Henning Groll
Original assignee: Biotul Ag
Priority date: 1998-02-12
Filing date: 1999-02-11
Publication date: 1999-08-19
Also published as: EP1161676A1; AU2623299A

Abstract

The invention relates to a surface plasmon resonance transducer, in which the properties of the surface (5) presenting surface plasmon resonance and/or the properties of at least one adjacent area (7, 8) are configured and/or modifiable in such a way that surface plasmon resonance can be measured by way of a spatially and/or time-resolved detection of the intensity of the radiation reflected by the surface.

Description

Determination of the surface plas on resonance with the help of locally or temporally modified layers

The invention relates to a device and a method for measuring surface plasmons.

Surface plasmon resonance (SPR) observes changes in both the thickness d and the refractive index n of a thin layer of a metal and any layers deposited thereon. Surface plasmons are collective excitations of the free electrons in a metal that can be excited by a light field that is reflected at the boundary of the thin metal layer. The excitation occurs when both the energy and the momentum of the incident light field match that of the plasmons. The surface plasmon resonance can thus both with the help of the variation of the wavelength (energy) of the incident light, 2

can be observed at a constant angle (pulse) and by varying the excitation angle at a constant wavelength. Both principles and equipment for their use are described in the article by Erwin Kretschmann, "The determination of optical constants of metals by excitation of surface plasma vibrations", Z. Physik 241, 313 - 314 (1971).

The position of the SPR in the spectrum does not depend solely on the properties of the plasmon-bearing layer of the free electron metal.

Rather, the position of the SPR and also its shape depend on the optical properties of the medium adjacent to the surface. This property is used for the use of the SPR in sensors. Particularly in biosensors, the adjacent medium is designed so that its optical properties (thickness and refractive index) are modified by specific adsorption of analyte molecules. This is typically done by firmly binding special ligand molecules in a thin layer that prevents unspecific adsorption. These ligands are specific binding partners for the molecules to be analyzed. For example, such a typical pair is an antibody (ligand) and the corresponding antigen (analyte). In this way, the presence and concentration of analyte molecules and the binding mechanisms between them and the modified sensor surface can be concluded with the aid of the shift in the spectrum or a general change in the SPR. The sensors generated in this way are called affinity sensors. With their help, the reaction between analyte in a sample solution and ligand can be measured in a time-resolved manner. Gunnar Brink provides an overview, "Self-organized ultra-thin layer systems based on proteins and lipid membranes; generation, characterization and application in bicensor systems", VDI Verlag. 3

The sensors described in the prior art and the underlying methods are based on observing the displacement of the SPR either in the spectrum of the incident light or in the excitation angle. The use of a method that is based on the spectral measurement of the SPR has the advantage that the location space is available for obtaining additional information. If the wavelength-resolved measurement is linked to a spatially resolved measurement, the information density can be increased significantly. The difference corresponds to that between a black and white screen and a color screen.

Both the angular and the wavelength-resolved measurement of SPR use the controlled change (tuning) of an external variable across the width of the resonance or the irradiation of light with the width of the resonance - spectrally, approx. 100 nm or more, angularly resolved , a few degrees - to measure changes in SPR. These methods have the disadvantage that they either cannot provide an optimal time resolution, an optimal energy density or neither of the two.

The invention has for its object to provide a device and a method for measuring surface plasmons, which enables better time resolution and / or energy density.

This object is achieved with the features of the claims.

Measuring the SPR with a spectrally narrow-band, parallel, constant light beam of high intensity is ideal in terms of time resolution and sensitivity. This means that both the temporal and the resolution when measuring intensities and thus the sensitivity can be optimized.

The invention is based on the basic idea that the material properties of those areas which adjoin the surface of the SPR sensor (transducer) carrying the SPR, 4

or so close - +/- 5 μm - to the SPR-bearing surface that they have a significant influence on the SPR, to be modified in such a way that a spatially or temporally resolved determination of the intensity of the radiation reflected from the surface enables the SPR to be measured .

These layers can be the free electron metal (metal layer) or a first layer on the light coupling side or a second (dielectric) layer on the sample side. The first and second layers can directly adjoin the metal layer. Alternatively, the first or second layer can be separated from the metal layer by a first or second intermediate layer or a plurality of intermediate layers. The second layer can also directly adjoin the sample volume. The form and location of the SPR are primarily influenced either spatially or temporally.

The invention enables the above-mentioned determination of the SPR both with an optimal temporal (only with spatially resolved determination) and with an optimal intensity resolution. It also has the advantage that the other spatial axes can optionally be used to obtain further information. This is made clear in the exemplary embodiments. In particular, the invention also allows the combination of spatially or temporally resolved measurements and narrow-band spectral modulation of the light source to suppress external disturbance variables and to achieve an optimal signal-to-noise ratio. Various methods are available for spatial modification of the transducer surface - more precisely: of complex refractive index n, thickness d or the product n * d. On the one hand, the thin layer of the free electron metal can be produced or modified in a correspondingly structured manner, or one or more layers which directly or indirectly adjoin the metal layer. Techniques available for modification are based on the spatially resolved application of material, such as spatially resolved sputtering of material on surfaces, or by printing, by directional diffusion of foreign materials, by spatially resolved ion implantation, by spatially resolved photo-induced binding or also by deliberately removing material from the surface, for example by sputtering or lithographic techniques, plasma etching etc.

A further possibility for the spatial modification according to the invention is the generation of a standing wave - for example as a density modification in an acoustic way - in the area of the transducer which adjoins the SPR-bearing surface.

Alternatively, it is possible to use a material at the interface whose refractive index can be modified in a spatially or time-resolved manner by irradiation with a further light field. Such a material is, for example, a dye.

In addition to determining the surface plasmon resonance by spatial modification of the transducer in the area that is sensitive to the shape and position of the SPR, the time-resolved modification of this area is also suitable for improving the detection of SPR and the sensors based on it. A time-resolved modification is understood here to mean the change in the properties of one or more layers in an SPR transducer, which are suitable for changing the shape and position of the SPR, in such a way that these changes are reversible and by changing a time external size come about. For example, one or more of the layers described or the entire transducer can be compressed or expanded, or the temperature of corresponding areas can be changed or a light field as described above can be irradiated. The invention is explained below with reference to exemplary embodiments with reference to the drawing. Show it:

Figure la: a schematic structure of a device for

Measurement of SPR, Figure lb: a schematic structure of an SPR sensor with a configuration according to Kretschmann for excitation of SPR, Figure lc: a schematic diagram of a section of a

Sensor according to Figure lb; FIG. 1d: shows a diagram of the strength of the electric field E in the border area free electron metal 5 / sample 6; Figure le: a schematic representation of a layer structure of the transducer area acting on the shape and position of the SPR; FIG. 2a: a schematic representation of a variation of the layer thickness d of the free electron metal 5 in an SPR sensor according to a first embodiment of the invention; FIG. 2b: a schematic representation of a variation in the layer thickness of an additional dielectric layer 7 between free electron metal 5 and sample 6;

Figure 2c: a schematic representation of a shift of a spatially resolved SPR signal; FIG. 3 shows a basic illustration of a variation of the refractive index n of the free electron metal 5 or of a layer 7, 8;

FIG. 4 shows a basic illustration of a cyclic variation of the optical properties of the free electron metal 5 or a layer 7, 8; FIG. 5a: a top view of a circular transducer 2 according to a further embodiment of the invention; FIG. 5b: a schematic arrangement of different sample channels 10 along the radius r of the circular transducer according to FIG. 5a; FIG. 5c: a basic representation of an SPR signal as a function of the angle of rotation in a transducer according to FIG. 5a; FIG. 6a: a perspective view of a sensor based on the rotationally resolved measurement of an SPR signal according to an alternative embodiment of the invention;

Figure 6b: a schematic structure of a device for

Measurement of SPR with a sensor according to the figure

6a;

7a shows a perspective view of a sensor with a linear arrangement for determining analyte concentrations with the aid of spatially resolved measurement of an SPR signal, and FIG. 7b shows a basic illustration of an SPR signal as a function of the location in a transducer according to FIG. 7a.

Exemplary embodiments of the invention are described below.

a schematic structure of an optical sensor is shown in FIG. A parallel light beam of constant wavelength is emitted from a light source 1, preferably a laser, e.g. a diode laser, irradiated onto an SPR transducer 2. The light emitted by the transducer is detected by a detector 3 and then evaluated by an evaluation unit (not shown).

The transducer 2 is used, for example, as shown in FIG. 1b in a Kretschmann configuration. The transducer consists of a free electron metal layer 5 on the light-coupling side of which a glass prism 4 is arranged. A sample 6 is arranged on the sample side of the metal layer 5. The light beam is emitted from one side of the glass prism 8th

mas 4, which serves as a coupling medium, directed onto the surface of the metal layer 5. The reflected light is output on an opposite side of the glass prism 4. As can be seen from FIG. 1c, which shows a section of FIG. 1b, there is a total reflection of the light on the metal layer 5. An evanescent field is formed in the metal layer 5 and the adjacent sample, which excites surface plasmons on the opposite side of the metal layer. The corresponding field course of the surface plasmons is shown in FIG. 1d. Surface plasmon resonance (SPR) occurs under certain conditions. This SPR changes depending on the conditions on the sample side. This change is used for the evaluation of the sample.

As shown in FIG. 1e, the transducer 2 can consist of several layers arranged one above the other. A first dielectric layer 7 is arranged on the light-coupling side, and adjoins the metal layer 5 directly or as shown via one or more first intermediate layers 7a. In the same way, a second layer 8 is arranged directly adjacent to the sample side or separated by one or more second intermediate layers 8a.

The structure or the surface of the transducer according to the invention is such that the thickness of at least one of the layers varies along at least one of its axes. The remaining layers are equally thick. Alternatively or additionally, the refractive index varies in at least one of the layers mentioned.

Figure 2a shows a preferred embodiment of a transducer according to the present invention. With this SPR sensor, the thickness of the layer of free electron metal 5 varies in the y direction. In the example, the thickness increases linearly from 40 to 50 nm from the left (from the first side of the prism) to the right (to the second side of the prism). Gold or silver, for example, is used as the free electron metal.

In an alternative embodiment of the invention, which is shown in FIG. 2b, the thickness of a thin glass layer 8 located on the sample side of a gold layer 5 varies in the y-direction of the transducer. In the example, the thickness changes linearly from 20 to 100 nm. The thickness of the gold layer 5 is uniform in this example. Alternatively, the thickness of the gold layer can also vary.

The intensity of the light reflected from the transducer surface is measured with a detector 3, which is designed in such a way that it permits measurements with spatial resolution in at least one dimension. The detector is, for example, a photodiode array that is arranged in the y direction. The resulting signal is a spatially resolved SPR. If the optical properties of the layer 6 adjoining the gold layer (FIG. 2a) or the glass layer (FIG. 2b) change, the SPR shifts as shown schematically in FIG. 2c. The shift is, for example, a measure of the analyte atoms bound in the adjacent layer.

Figure 3 shows a further embodiment of the invention. The optical structure corresponds to the exemplary embodiment in FIG. 1b. The transducer surface is designed such that the refractive index n of the layer of free electron metal 5 or another layer 7, 8 increases along a transducer axis, as shown in the diagram. As in the exemplary embodiments in FIGS. 2a and 2b, the resulting signal is a spatially resolved SPR. A combination of the exemplary embodiments of FIGS. 2a and 2b with that of FIG. 3, in which the optical properties correspond to the product of thickness d and refractive index.dex n, leads to a corresponding effect. 10

In the exemplary embodiment in FIG. 4, the optical properties d * n of the plasmon-bearing layer 5 or another layer 7, 8 are varied cyclically. The product n * d indicates the variation in the thickness d and / or the refractive index n that is present in the y-direction of the transducer. The amplitude of the cyclic modification of the optical properties is preferably just large enough to sweep the entire SPR in one period. This cyclic variation can e.g. corresponding to a sawtooth-shaped function, a triangular function, a sine function or, for example, a function which maps the surface plasmon to one of the functions mentioned.

The underlying coordinate system is not necessarily a rectangular one, as shown in Figures 1 to 4. For example, a circular transducer can also be used - FIG. 5a. Then the corresponding coordinate in the exemplary embodiments described above is no longer y but the angle of rotation and the spatially resolved measurement of the intensity with the aid of a diode line or a camera can be carried out by detection with a photodiode and simultaneous rotation of the circular transducer. Such a structure is shown in Figure 5a. The rotation can be uniform or stepwise. In gleichför- miger rotation and for example, a surface which is designed such that the plasmon is being mapped to a period of a sine function in a complete rotation, the signal ^'of the photodiode can be read out just when the rotation frequency. A shift in the SPR can then be measured, for example, as a phase shift. For this purpose, a reference signal of constant phase is preferably recorded simultaneously with the actual measurement signal and a comparison is carried out with the aid of a PLL circuit (phase locked loop). As already mentioned above, the second dimension of the transducer surface can be used to provide further information about the sample to be examined. Example 11

Different ligands for different analytes or ligands of different affinity for one or more analytes can be applied in a affinity sensor along the x-axis (see FIG. 1b) or the radius r (see FIG. 5b). For example, the concentration of the ligands on the surface can also be varied along the x-axis or from r. Likewise, a number of different sample channels, which run correspondingly (in the form of concentric circles in FIG. 5b), can be used with different samples.

In accordance with the above embodiment and the methods and general embodiments described there, very greatly simplified affinity sensors can be implemented. In particular, completely new devices can be implemented for use as diagnostic affinity sensors. Two of these devices are described below as preferred embodiments of the invention with reference to FIGS. 6 and 7.

The device described here and shown schematically in FIG. 6 is based on the use of a circular transducer surface with concentric semicircular sample channels 10. A laser diode or, for example, a light-emitting diode serves as light source 1, the spectral width of which is restricted by the use of an optical filter or any other another light source with a spectral width that is small compared to the spectral width of the surface plasmon with a constant angle of incidence of the exciting light, or a light source that is provided with a spectral filter, such as a monochromator. With a resonance wavelength of approx. 780 nm, an approx. 50 nm thick, flat gold layer as transducer surface and the corresponding radiation angle, the SPR is approx. 100 nm wide (2 * FWHM - Fill Width Half Minimum). An LED in this wavelength range with a spectral width of the emitted light of approx. 15 nm - 30 nm is already small enough 12

to enable a corresponding measurement of the surface plasmon.

For a higher accuracy of the measurement of the SPR, a much narrower band light source is preferably used. Such a light source is a laser diode that shines at the wavelength mentioned with a spectral width of approximately 1 pm or less. The incident light is applied as parallel as possible. The measure for a tolerable deviation from parallelism is preferably the width of the SPR in the angular space at a constant wavelength of the incident light. Under the above conditions, this width is approximately 2 degrees, so that a light beam should have a convergence or divergence angle of approximately 0.5 ° or less. The required parallelism relates to the angle of incidence in the reflection plane. This parallel, monochromatic light beam is widened, for example by means of a beam forming optics 11 of cylindrical lenses in the direction perpendicular to the reflection plane, ^~ so that a "light curtain" is formed. The light beam designed in this way is coupled into a cylindrical prism 12, for example made of BK7 glass. This cylindrical prism is arranged in such a way that a disc, for example also with a BK7 surface, rotates past as a coupling layer 13 at its base. A layer for refractive index adjustment 14, for example silicone oil, is placed between the base of the prism and the rotating disk. Instead of a liquid, for example, a cushion made of silicone rubber between the prism and the rotating disk can also be used to adjust the refractive index. On the side which is arranged opposite the prism, the disk carries a layer of a free electron metal 5, for example gold, and possibly one or more further layers 7, 8, for example glass and dextran. These are modified in accordance with the above statements so that the SPR is a function of the angle of rotation. Along the radius of this disk, chambers or channels 10 are arranged opposite the prism, the various samples 6 13

contain. These channels can be extended over a wide angular range. They first serve to functionalize the sensor surface, ie. H. With the help of a certain sequence of chemical reactions, ligands are immobilized on the sensor surface. The samples to be examined can then be applied. As already said, the channels can be extended over a large range of the rotation angle Φ. A sequence of different chambers, for example with a sample and buffer solution, is also useful. Where u. U. The arrangement of the complete system can be such that the actual intensity measurement always takes place in an area with buffer solution, since the SPR signal in affinity sensors is always dependent on the optical properties of the medium that is adjacent to the sensitive surface. The reflected light is detected with spatial resolution along the radius r of the rotation, for example with the aid of a photodiode array, a CCD line or a camera. The information on shape and position is now obtained for each individual channel in a time-resolved manner, corresponding to the rotation of the transducer disc. If you are only interested in the position of the SPR, the appropriate determination of the phase (exemplary embodiment according to FIG. 4), the determination of the phase of a periodic SPR signal is sufficient. If enough time is available for the measurement, a step-by-step sampling of the SPR signals from the individual channels is also conceivable. In this way, the synergy with the modern CD player technology is extensive.

The exemplary embodiment of an SPR system described with reference to FIG. 6 is suitable for the simultaneous determination of a large number of analytes and, for example, their concentrations. The number of information that can be determined independently depends only on the possibility of generating systems for handling the samples with a sufficient packing density and modifying the surface with a corresponding resolution 14

can and provide a corresponding spatial resolution for optical detection.

FIG. 7 shows an alternative system which, similar to that from the exemplary embodiment in FIG. 6, obtains the spatial resolution required for the SPR measurement technology according to the invention from the movement of the transducer chip or the transducer disk. This system is particularly characterized by a simple structure. In addition, the energy required to move the transducer is low. Low energy is also required to operate the light source 1, the detector 3 and the evaluation and display units. The system can be operated with a battery. The energy can preferably be obtained from the conversion of mechanical energy or from light energy. This enables the device to be operated independently of the mains. Only a few parallel channels are used. In addition to the rotation of the transducer 2, the possible movement form here is in particular the linear displacement of the transducer in the direction of the SPR axis, which queries the status of a reaction after a certain time - for example after the equilibrium of the corresponding reaction has been reached. Such a system can be used, for example, for self-monitoring of patients with diseases in which crisis-related complications can be predicted by monitoring (monitors) certain factors, for example in the serum. This enables the patient to take countermeasures at an early stage. The system includes, in particular, an optical structure in accordance with the exemplary embodiment in FIG. 1. The transducer chip is moved along the y axis. The movement takes place, for example, driven by a spring that is simply tensioned, for example by rotation (restlessness) or by pulling apart or compressing it. For example, with the same movement or a second movement, a further spring is tensioned, which uses the energy to operate the light sources, the detector and the electronic ones 15

Provides evaluation and display facilities. Alternatively, the electrical energy for operating the detection system is made available with the aid of a photovoltaic system, a battery or an accumulator for charging via the electrical network.

The measurement in different channels is carried out either by multiplying the optical and / or the electrical measuring system or by time-delayed observation of the different channels, or by using a light source which is imaged in a light curtain along the y-axis in accordance with the exemplary embodiment of FIG. 6 and then either time-shifted with a photodetector or simultaneously with the aid of several photodiodes, a photodiode line, a CCD line or an adapted arrangement of photodetectors. The modification of the surface can follow certain continuous functions, as suggested in the previous examples, but can also be step-like. The latter surface modification is particularly useful when a YES / NO answer is required, as is often the case in diagnostic systems. Part of the surface (A) is designed so that in the normal state the reflected intensity is minimal (small), whereas in another part of the surface (B) the reflected intensity is large - A = 0, B = 1 -. If the state now deviates strongly from normality, the intensity becomes large at A and small at B A = 1, B = 0. Under certain circumstances, the states A = 0, B = 0 and A = 1, B = 1 can also be used to display information.

The exemplary embodiments according to FIGS. 1 to 7 describe the spatially resolved measurement of SPR or technical devices based thereon. In accordance with what has already been said above, the necessary local variations of layers 5, 7 and 8 can be replaced by corresponding reversible temporal modifications. Options for this are, in particular, variations in the refractive index of one or more appropriately designed layers 5, 7 and 8 16

Irradiation of strong light fields, coupling of density fluctuations or temperature changes. The resulting SPR signal is measured in a temporally resolved manner and its shape and position when irradiated with parallel, monochromatic light is determined with respect to the time axis and used as information in corresponding sensor systems.

17

Reference list

5 1. Light source

2. Transducer

3. Detector

4. Coupling medium 5. Free electron metal

10 6th rehearsal

7. Dielectric layer (light coupling side) 7a. Intermediate layers (light coupling side)

8. Dielectric layer (sample side) 8a. Intermediate layers (sample side)

I ⁵ 9. Circular transducer

10. Sample channels

11. Beam shaping optics

12. Cylinder prism

13. Coupling layer

20 14. Refractive index matching layer

25

30

35

Claims

18 patent claims

1. Surface plasmon resonance transducer _/ in which the properties of the surface plasmon resonance-bearing surface (5) and / or the properties of at least one adjacent area (7, 8) are designed and / or changeable such that the spatial and / or temporally resolved determination of the Intensity of the radiation reflected from the surface, the surface plasmon resonance is measurable.

2. Transducer according to claim 1, wherein the adjacent region is at a distance of up to +/- 5μm from the surface which carries the surface plasmon resonance, or is adjacent thereto.

3. Transducer according to claim 1 or 2, wherein the material properties of the surface plasmon resonance-bearing surface (5) and / or the adjacent region can be changed such that the shape and position of the surface plasmon resonance can be spatially and / or temporally influenced.

4. Transducer according to one of the preceding claims, wherein the surface plasmon resonance-bearing surface has a metal layer (5) and the adjacent region has at least one layer (7, 8).

5. Transducer according to claim 4, wherein at least one layer (7) on the light coupling side of the transducer and / or at least one layer (8) is arranged on the sample side of the transducer.

6. Transducer according to claim 5, wherein at least a first intermediate layer between the metal layer (5) and a first layer (7) on the light coupling side 19

(7a) is arranged, and / or at least one second intermediate layer (8a) is arranged between the metal layer (5) and a second layer (8) on the sample side.

7. Transducer according to claim 5 or 6, wherein the metal layer (5) comprises a free electron metal, preferably gold or silver.

8. Transducer according to one of the preceding claims, wherein the first or second layer (7, 8) and / or the first or second intermediate layer (7a, 8a) is a SiOx layer

(0 ≤ x ≤ 2), in particular a glass layer.

9. Transducer according to one of claims 4 to 8, wherein at least one layer of the transducer has a changing complex refractive index n in at least one direction.

10. Transducer according to one of claims 4 to 9, wherein at least one layer of the transducer has a thickness d that changes in at least one direction.

11. Transducer according to one of claims 4 to 10, wherein the thickness of the metal layer (5) varies in at least one direction of the transducer, preferably in at least one section the thickness increases in at least one direction of the transducer, and particularly preferably the thickness of the metal layer in linearly increases in at least one direction from, for example, 40 to 50 nm.

12. Transducer according to one of claims 4 to 11, wherein the thickness of a further layer (7, 7a, 8, 8a) varies in at least one direction of the transducer, preferably in at least one section the thickness increases in at least one direction of the transducer and particularly preferably the thickness of the layer in at least one 20th

Direction increases linearly from, for example, 20 to 100 nm.

13. Transducer according to one of claims 10 to 12, wherein the variable thickness of the metal layer (5) and / or further layer (7, 7a, 8, 8a) directed by spatially resolved application of material, such as sputtering gold on surfaces, printing Diffusion of foreign materials, ion implantation, or by photoinduced binding is provided, and / or by targeted removal of material from the surface, as is provided by sputtering, lithographic techniques and / or plasma etching.

14. Transducer according to one of claims 9 to 13, wherein the refractive index n of the metal layer (5) and / or the further layer (7, 7a, 8, 8a) varies in at least one direction of the transducer, preferably in at least a section of the Transducers increases linearly in one direction.

15. The transducer according to claim 14, wherein the variable refractive index n is provided with fixed gradients by spatially resolved introduction of material, such as directional diffusion of foreign materials or ion implantation.

16. Transducer according to one of the preceding claims, wherein the transducer has at an interface a material whose refractive index n can be modified in a spatially resolved manner by irradiation of a light field.

17. The transducer of claim 16, wherein the material at the interface of the transducer is preferably a dye. 21

18. Transducer according to one of claims 4 to 17, wherein at least one layer (5, 7, 7a, 8, 8a) in at least one section of the transducer reversibly changes its properties by changing the external size over time.

19. Transducer according to claim 18, wherein at least one layer (5, 7, 7a, 8, 8a) of the transducer can be changed in its density, preferably the density can be changed by an acoustic signal, particularly preferably the change in density in the form of a standing acoustic wave provided.

20. Transducer according to claim 19, wherein the layer (5, 7, 7a, 8, 8a) is compressible or expandable.

21. Transducer according to one of claims 18 to 20, wherein at least a section of a layer (5, 7, 7a, 8, 8a) changes its properties by time-dependent temperature change.

22. Transducer according to one of claims 18 to 21, wherein at least one layer (5, 7, 7a, 8, 8a) can be changed as a function of an irradiated light field.

23. Transducer according to one of claims 18 to 22, wherein the transducer has at an interface a material whose refractive index n can be modified in a time-resolved manner by irradiation of a light field.

24. The transducer of claim 23, wherein the material at the interface of the transducer is preferably a dye.

25. Transducer according to one of claims 1 to 24, with at least one layer (5, 7, 7a, 8, 8a), the optical properties of which can be changed cyclically. 22

26. Transducer according to claim 25, wherein an amplitude of the cyclic modification of the optical properties is preferably so large that a complete surface plasmon resonance is swept in one period.

27. The transducer according to claim 26, wherein the cyclic variation follows a sawtooth-shaped function, a triangular function, a sine function or a function that maps the surface plasmon to one of said functions.

28. Transducer according to one of claims 1 to 27, wherein a change in the properties of the transducer takes place in one direction in a Cartesian coordinate system, preferably in the direction of an axis y of a rectangular transducer.

29. Transducer according to one of claims 1 to 27, wherein a change in the properties of the transducer takes place in one direction in a cylindrical coordinate system, preferably in the direction of the angle of rotation of a circular transducer.

30. Optical sensor with a light source (1); a surface plasmon resonance transducer (2) in particular according to at least one of the preceding claims and a detector (3).

23

31. Optical sensor according to claim 30, wherein a coupling medium (4, 12) is arranged on the light coupling side of the transducer and the transducer is linearly movable relative to the coupling medium (4, 12).

32. Optical sensor according to claim 31, wherein the transducer

(2) movably arranged along at least one direction and connected to a drive.

33. Optical sensor according to claim 31 or 32, wherein a sample space is provided on the sample side of the transducer, which preferably has a plurality of sample channels (10).

34. The optical sensor of claim 33, wherein the transducer

(2) is rectangular and at least one sample channel (10) is arranged in the direction of movement of the transducer, each sample channel preferably extending over an area which is between 5% and 100% of the path of movement of the transducer.

35. Optical sensor according to claim 30, wherein a coupling medium (4, 12) is arranged on the light coupling side of the transducer and the transducer is rotatable relative to the coupling medium (4, 12).

36. Optical sensor according to claim 35, wherein the transducer is rotatably arranged about an axis and is connected to a drive. 24

37. Optical sensor according to one of claims 35 or 36, wherein a sample space is provided on the sample side of the transducer, which preferably has a plurality of sample channels

(10).

38. Optical sensor according to claim 37, wherein the transducer

(2) is circular and at least one sample channel (10) is arranged concentrically, each sample channel preferably extending over a well-defined area which is between 10 ° and 360 °.

39. Optical sensor according to one of claims 31 to 38, wherein the coupling medium has a triangular prism (4) or a cylindrical prism (12) or a portion of a prism.

40. Optical sensor according to one of claims 31 to 39, wherein a means for adjusting the refractive index, preferably an immersion sol (14), is arranged between the light coupling-in side (13) of the tranducer (2) and the coupling-in medium (4, 12) .

41. Optical sensor according to one of claims 31 to 40, wherein a metal layer is arranged directly on the coupling medium (4, 12) on the light coupling-in side (13) of the transducer (2).

42. Optical sensor according to one of claims 34, 38 to 41, wherein each sample channel (10) has different chambers for receiving, for example, a sample or a buffer solution. 25th

43. Optical sensor according to one of claims 31 to 42, wherein the light source has a spectral width which is small compared to the spectral width of the surface plasmon at a constant angle of incidence of the exciting light and / or emits a substantially parallel light beam.

44. Optical sensor according to claim 43, wherein the light source comprises a laser diode or light-emitting diode with a spectral filter such as a monochromator.

45. Optical sensor according to one of claims 31 to 44, with a beam shaping optics (11) preferably made of cylindrical lenses, which expand the light beam from the light source (1) in the direction perpendicular to the reflection plane and form a parallel monochromatic light beam.

46. Optical sensor according to one of claims 31 to 45, wherein the detector (3) has a plurality of photodetectors, preferably in the form of a photodiode array, a photodiode array, a CCD line or a camera or a customized arrangement of photodetectors.

47. Optical sensor according to one of claims 31 to 46, wherein the transducer (2) at least two areas

(A, B), wherein in a normal state the reflected intensity is small in a first region (A) and in a second region (B) the reflected intensity is large and when the deviation from the normal state the reflected intensity in regions (A , B) changes.